Automatic test method for an inspection device

ABSTRACT

The invention relates to a test method for examining an inspection device, which is associated with a functional unit of a master unit, comprising at least the following steps: producing a specified number of faulty and/or correct containers or test containers by means of the functional unit itself in that a control signal for producing a distinctive element is fed to the functional unit; leading the faulty containers or test containers past the inspection device, which detects the faulty containers or test containers and produces a signal to discharge the faulty containers or test containers, or indicates a value regarding the expected and the measured faulty and/or correct containers. The test method is automatically started or performed and is suitable, for example, for examining a label position checking device, the filling amount checking unit, and the closure seating checking unit in order to be able to determine the fault-free functioning thereof or optionally the faulty functioning thereof. The test method is characterized in that operation is not required. The test method is characterized in that the test method allows clear and documented rules for the procedure and the test results, which ensure quality control in terms of product liability.

The invention relates to a test method for examining an inspection device which is associated with a functional unit of a master unit.

DE 10 2004 005 994 A1 discloses a labelling machine. The latter having an apparatus for the feeding of labels and a labelling unit. The labelling unit has a label container, a glue roller, a rotatable carrier provided with gluable withdrawing segments, and a gripper cylinder. Thus for example bottles can be provided with labels, whereby the labelling machine can be configured for example as rotary-table-type machines, linear machines or horizontal-table-type machines. In the exit area of the labelled bottles is disposed a label position checking device which monitors the desired orientation of the labels on the bottles. It is conceivable for labels to be checked for correct location for example relative to design features (so-called embossings) disposed on the bottles. It is also possible to check neck and body labels for correct alignment either relative to one another or to the design features. In the event of a change in the label location beyond a definable tolerance, the label position checking device conveys corresponding signals to trigger a correction device which acts on the labelling units so that a correct label position can be achieved. The bottles which are not provided with a correctly positioned label are of course ejected via an outward transfer apparatus, this of course also being possible by way of the correspondingly generated signal of the label position checking device.

DE 44 41 245 A1 discloses a method for checking labelled vessels. The checking device is integrated in a labelling machine and is equipped with a laser distance meter. The laser distance meter can be used to determine whether a container is provided with a label or not. During an active measuring interval the laser beam emitted by the laser distance meter first strikes the surface of a passing bottle and measures the latter's distance from its fixed-position housing, which therefore forms the constant point of reference. As soon as the laser beam strikes the surface of the label, there is an abrupt decrease in the instantaneously measured distance equivalent to the thickness of the label and to the film of adhesive, if any, between the bottle and the label. This abrupt change of distance is captured in an evaluator and evaluated as a criterion for the presence of a label. Accordingly the evaluator sends either no signal or a ‘good’ signal to a sorting apparatus. If there is no label on the bottle, no abrupt change of distance can be detected, so that the evaluator sends an error signal to the sorting apparatus which ejects the bottle concerned. The fact that the checking device can only determine whether a label is present on the bottle or not must be regarded as a major shortcoming. What it cannot determine on the other hand is whether the label is also correctly aligned relative to design features for example, or has creases.

DE 10 2006 022 492 A1 discloses a test container for a container checking device, having a large number of first marking rings which surround at least sections of the test container at predetermined, fixed heights and having a large number of marking lines running in a longitudinal direction of the test container, wherein the first marking rings are each disposed at constant, specified intervals in the longitudinal direction of the test container relative to one another, the marking lines intersect at least a part of the first marking rings and the marking lines are each disposed at predetermined intervals in a peripheral direction of the test container relative to one another. This is intended to facilitate a simplified adjustment of a camera to be changed in the checking device.

Bottles or similar containers for example are filled with a filling material by a filling apparatus and then passed to a labelling machine. The containers are aligned in the labelling machine or previously, relative for example to design features (so-called embossings), so that the labels can be affixed to the containers oriented relative to the design features. The labelled containers are again aligned and guided or conveyed past an inspection device which can be configured as a label position checker. If the label position checker detects containers with a bad or faulty label location, a signal for ejection is generated. The ejected containers, e.g. bottles, are stored on a separate conveyor.

Of course the inspection device, in the configuration as a label position checker for example, needs to be checked for correct operation. This can be done by checking the rejected containers, for example. However this approach is very time-consuming and unreliable, especially since the containers that were not rejected can only be checked randomly because the container flow moves at high speed. Labelling machines for example have a throughput in excess of 60,000 containers or bottles per hour.

DE 10 2008 050 249 A1 which goes back to the applicant relates to a test method for inspection devices, especially for label position checking devices. The test method described here has proven to be advantageous in practice because the inspection device can be reliably checked for correct operation. This is done advantageously by generating an individually predetermined number of test containers which are conveyed past the inspection device. If functioning correctly, the inspection device will also send a corresponding signal to an ejecting apparatus instructing it to eject at least faulty containers. An evaluator can of course be connected between the two devices. If the inspection device detects all faulty containers, and/or if all faulty test containers are ejected, and leaves fault-free test containers in the container flow, it is ensured that the inspection device is operating correctly.

According to the teaching of DE 10 2008 050 249 A1 the individually predetermined number of test containers is generated manually, which means that they are manually inserted into the container flow. If the test programme is detected, at least the labelling function is switched off. The functional unit and/or labelling unit is automatically switched off when the test method is sequencing automatically. The test programme can be run regularly, e.g. daily, before each shift change or before a product change.

The fact that only a low sampling depth can be achieved is felt to be a disadvantage, for the test programme is only run once per shift, for example. Manual interventions on the other hand can result in increased operating errors. The issue of product liability in particular plays a part here, because a very great effort for documentation is required. A further disadvantage is felt to be that for example the labelling function is switched off when the test programme is detected. However switching off the labelling function for example simultaneously involves a production interruption during the test and results in a loss of efficiency for the installation.

The object of the invention therefore is to provide a test method for examining an inspection device, by which (method) for example the effectiveness of the treatment installation is less adversely affected despite the performing of the test method, and wherein the particular test which is performed can at the same time be documented with less effort.

According to the invention the object is resolved by a test method having the features of claim 1, comprising at least the following steps: generating a specified number of containers, so-called test containers, by the functional unit itself, in that a control signal for generating a distinctive element is fed to the functional unit; leading the test containers past the inspection device which detects the test containers and ideally generates a control signal.

The correct operation of the inspection device can be reliably examined with the invention, without requiring intervention by an operator. Moreover the test method can be carried out without the functional unit having to be switched off. Because the examination of the inspection device is fully automated, a significantly reduced documentation effort is expected since all steps are effected automatically and each individual step is accordingly consolidated automatically at a suitable point and automatically archived or stored. The documentation can be retrieved at any desired time. The automatic test method is of course not bound by particular points in time such as shift changes, but can be carried out advantageously at any desired time, preferentially randomised.

What is of the essence is that the specified number of test containers is generated by the functional unit itself, so that an automatic self-monitoring can be achieved. The master unit can be typically configured as a container treatment installation, e.g. in the embodiment of a bottle treatment installation, which exhibits as functional units e.g. a filler, a labeller and/or a capper, to name just a few functional units by way of example.

In the functional unit ‘filler’ for example, a distinctive element or defined error may be that a quantity that differs from the nominal quantity is filled into a container. In the functional unit ‘labeller’, a defined error may for example be a skewed label that is applied. In the functional unit ‘capper’, an incomplete capping may for example be generated as a defined error. Consequently an underfilling, an overfilling, a positional inaccuracy of the label or a missing label, a missing cap, too high a cap seating, too low a cap seating and/or an incorrectly seated crown stopper may for example be generated as defined errors, to name just a few distinctive elements or defined errors by way of example.

In this respect the invention is based on the knowledge that the functional units are in any case each networked with the master unit or with the latter's control unit. The control unit can for example trigger the functional unit ‘filler’, whereby electronic fillers can trigger individual valves which generate the defined error. With the functional unit ‘labeller’, servo-driven stations can moreover be selectively de-synchronised. The label feed at the dispenser station or the angle of rotation of the transport plate for the bottle carrier for example can be selectively triggered. The functional unit ‘capper’ also exhibits servo-driven capping elements that can be selectively triggered.

The generating of the defined error is of course only carried out during the test method. It is an advantage in this respect that the control unit is networked with the error-generating functional unit, so that the control unit knows and/or stores this error. The inspection device connected downstream of the functional unit should detect the defined error and transmit an ejection signal to the corresponding ejecting apparatus, or alternatively a signal to eject the test container concerned is generated. However because the control unit ‘knows’ the test container and is also preferentially networked with the ejecting apparatus, it is possible in this way to establish whether the inspection device is operating correctly. For if the faulty test container reaches the sorting apparatus and remains in the container flow, i.e. is not ejected, this is a sign of a malfunction of the inspection device. This is duly indicated e.g. by way of acoustic warning tones or even an emergency stop, at least of the functional unit concerned, to allow the inspection device concerned to be manually examined. It is of course wholly to the purpose of the invention for the fully automatic test method for examining the inspection device to be carried out with ‘good’ containers as well. In this instance, the test method is started and no defined error/distinctive element is generated by the functional unit itself. This test container with a correctly located label for example, is therefore conveyed past the inspection device. Because the control unit ‘knows’ the position of the test container in the container flow, when the test container reaches the ejecting apparatus the control unit expects a ‘good’ signal, i.e. a signal which leaves the test container in the container flow. If the test container is ejected however, this is again duly indicated.

It is also essential that the particular functional unit whose associated inspection unit is to be examined is not switched off. This is because the functional unit itself generates the defined error or the ‘good’ test container. By the corresponding signal being transmitted to the functional unit, the latter can itself generate one single test container or a plurality of test containers as the specified or randomised number of test containers. Once the specified number of test containers has been generated, the functional unit can be returned directly to its normal mode by its receiving the corresponding signal. In the past, the specified number of test containers was introduced manually into the container flow upstream of the functional unit, with the functional unit being switched off. In this case the test containers travel a relatively long distance until they reach the inspection unit that is to be examined, which naturally consumes a considerable period of time during which the functional unit is switched off. The invention on the other hand obviates the need for this introduction of test containers into the container flow at the inlet end, with the result that the test method is of relatively short duration, being naturally dependent on the random number of test containers. The test container is preferentially generated by the functional unit itself in a randomised manner from a random container in the container flow.

A specified number of test containers which are conveyed past the inspection device is therefore advantageously generated. If functioning correctly, the inspection device should also send a corresponding signal to the ejecting apparatus instructing it to eject at least faulty containers. An evaluator can of course be connected between the two devices. If the inspection device detects all faulty containers, and/or if all faulty test containers are ejected, and leaves fault-free test containers in the container flow, it is ensured that the inspection device is operating correctly.

In a favourable embodiment it is proposed that the inspection unit inspects the test container or test containers and generates a measured value by means of which the number of test containers with defined error can be determined, wherein the variance between the nominal measured value and the actual measured value can be determined by means of the measured value, with ideally the nominal measured value being the specified number of test containers with defined error, i.e. being the number of test containers that is stored in the control unit, and the actual measured value being the number of test containers with defined error as measured or captured by the inspection device.

It may be expedient for the purpose of the invention for the inspection device to generate a signal for ejecting at least those test containers with defined error.

In any test method or test programme a different number of faulty test containers can of course also be generated by the functional unit itself, which is what is meant by the term ‘randomised number’ in the sense of the invention. It is also advantageous for the inspection devices concerned to be examined simultaneously. For example the functional unit ‘labeller’ could generate a label location that is not aligned on so-called embossings while at the same time the respective functional unit ‘filler’ generates an underfilling at the same test container and the functional unit ‘capper’ generates an incorrect capping of the same test container. This is possible because the control unit ‘knows’ the position of the test container concerned and can therefore trigger the respective functional units and verify whether the particular inspection device generates the corresponding control signal. In this way a test container is advantageously generated with the defined error by the respective functional unit, such that the number of test containers that must be be ejected is reduced, which has the beneficial effect of reduced rejects and increased efficiency. Different test containers can of course also be generated by the particular functional unit itself, thereby generating as it were a test container flow.

It is however also essential that the test method is carried out in a randomised manner, meaning that all or part of the inspection units can be examined in a randomised manner simultaneously or at random points in time independently of one another. If all or part of the inspection units are examined in a randomised manner simultaneously, then an approach can be adopted whereby the examination begins with the first functional unit/inspection unit upstream. This means that when the first functional unit upstream is duly randomly triggered to generate the distinctive element/defined error, the randomisation of the others is disabled, and can be triggered to generate the defined error. An alternative—for example randomly determined—sequence is equally possible.

If it is operating correctly, the respective inspection device should detect the faulty test containers so that a signal for ejecting the faulty containers is generated in the known manner.

As already suggested above, for the further examination of the inspection device or label position checker, provision can of course also be made for at least one ‘good’ container to be conveyed past the inspection device as a test container which, if the inspection device is operating correctly, should not be ejected or which preferentially is ejected but is identified as being in order.

In a preferred embodiment of the method, provision can be made to create a combined test container flow of the functional unit concerned and/or of all and/or of some of the functional units, said flow comprising a randomly specified number of faulty and non-faulty test containers, i.e. to create a combined test container flow from, for example, correctly labelled and incorrectly labelled, and/or underfilled or overfilled and correctly filled, and/or incorrectly and correctly capped test containers. This combined test container flow is conveyed en bloc past the inspection devices. If the inspection device concerned is operating correctly, the fault-free test containers remain in the test container flow, with the faulty test containers being ejected. Here again of course the fault-free test containers can be ejected but then identified as being in order.

The invention provides a test method for the self-checking of an inspection device, in the preferred embodiment as a label position checking device, by which (test method) an examination of the correct operation of said device can be carried out reliably; a plurality of test runs, for example per shift, is of course possible. In a preferred embodiment, the inspection device concerned can be additionally connected to an inspection screen so that the result is displayed as soon as the containers have passed by the inspection device, allowing a judgement on the correct operation of the inspection device to be directly made at the same time. It is also of the essence that not only a visual examination is possible, since the position of the test container provided with the defined error, or of the error, is—as stated above—‘known’, such that an automatic self-monitoring is advantageously made available. Said self-monitoring requires no operator intervention, which of course avoids not only the operating itself but substantial operator costs as well. A benefit that is not to be underestimated is the constantly uniform and even examination of quality from which error sources arising through operation are precluded. Execution is fully automatic with no intervention on the part of the operator.

The test method is characterised by the fact that it permits clear and documented rules for the method and the test results, rules which ensure, or at least greatly simplify, a quality control in the interest of product liability.

Once the test containers have been generated by the functional unit itself, the latter is automatically returned to its original function.

The invention is suitable in preferred applications for any inspection machines/apparatus and monitoring machines. To this extent the inventive test method can be implemented for example on labelling machines for verifying the Inlabeler label location and embossing alignment check so as to allow the owner-operator of the labelling machine to establish at any time whether the said check is operating correctly or whether for example maintenance work and/or adjustments are necessary. In particular the inventive test method can also be used on other inspection devices in order to verify their correct operation by means of a specified number of ‘bad’ containers (and ‘good’ containers).

The advantages of the invention can be established for example by reference to data mentioned by way of example only and having no limiting effect, a purpose which flowcharts A and B are intended to serve. Flowchart A shows a test method according to the prior art. Flowchart B shows a procedure according to the present invention. The two flowcharts A and B are depicted side by side to show that considerable time and hence cost is saved with the inventive procedure.

In flowchart A, the procedure is started at block 1 by an operator or a laboratory generating an individually specified number of test containers. A manufacturing time of for example three minutes is assumed for this. The test method is started at block 2. The operator conveys the test containers to—for example—the labelling machine for this purpose. During this illustrative period of five minutes, the operator is not available at the notional labelling machine. The test method is started by the test containers being manually introduced into the container flow. At block 3, a marked test container is placed in front of the test containers so that the start of the test programme can be verified (this has been described in detail in DE 10 2008 050 249 A1, which is deemed to be comprehensively disclosed here). A time of, say, 30 seconds—in which the risk of a production stoppage or production interruption can be considerable—is allowed for this step 3. In block 4, the test container is supposed to be detected by the sensor system; there can be an attendant risk of a minimal sensor system. In block 5 the detected test container is entered in a register. In block 6 the test container is measured and positively ejected, with the test container being disposed of in block 7. Blocks 4 to 7 are negotiated in an assumed time of 30 seconds. In all therefore, a time of nine minutes is needed for a state-of-the-art test method. During this period of time therefore the operator is engaged on activities alien to his actual tasks.

In flowchart B according to the present invention on the other hand, at the start of the examination of the inspection device in block 8 the functional unit itself generates a desired error on a container taken at random from the container flow, thereby creating the test container. The desired error is created by an appropriate instruction (signal) to the functional unit. The location, i.e. the site and the error, is unique. Unlike block 1 in chart A, no time is lost here because the desired error is automatically generated by the functional unit itself. In block 9 the system starts autonomously and fully automatically with its test cycle. In block 10 the test container is measured and positively ejected. The test container is disposed of in block 11. Blocks 10 and 11 are shown directly adjacent to blocks 6 and 7 in chart A because the same steps are carried out in them. As with chart A, a time of 30 seconds is assumed here. It can be seen that chart B contains no blocks equivalent to blocks 3, 4 and 5. To this extent therefore, a time advantage of 30 seconds is gained by eliminating the original steps according to blocks 3 to 5 in chart B. What is also of the essence however is that in blocks 8 and 9 too, no operator time accrues, because the procedure here is fully automatic. To this extent there is an advantage of three minutes over block 1 of chart A and a time advantage of five minutes over block 2 of chart A. Chart B provides an overall time gain of 8.5 minutes (=3+5+0.5) compared with chart A. Assuming an hourly wage rate of EUR 40, this would result in a saving on operator costs of approximately EUR 3400 per annum. On the other hand, instead of the three examinations carried out according to chart A, 17 (seventeen) test methods could be carried out with the procedure according to chart B for the same cost as the three examinations with the procedure according to chart A. With the inventive procedure according to chart B therefore, a correspondingly greater sampling depth is achieved for the same cost, allowing clear and simple documentation to be created. If the inspection unit does not operate correctly, an error message is automatically generated, leading to a substantial reduction in error reporting/error tracing time and resulting in a shorter response time. It is also important that with the inventive procedure, production is not interrupted, i.e. there is less loss of efficiency because the functional unit is not switched off while the test method is in progress. 

1-15. (canceled)
 16. A test method for examining an inspection device associated with a functional unit of a master unit, said method comprising: generating a specified number of test containers, by the functional unit itself, by feeding, to the functional unit, a control signal for generating a distinctive element; and leading the test containers past the inspection device, which detects the test containers and generates a control signal.
 17. The test method of claim 16, wherein generating the test containers comprises generating the test containers in a randomized manner, whereby the test method is carried out at randomized times.
 18. The test method of claim 16, further comprising selecting the master unit to be a bottle treatment installation, and selecting the functional unit from the group consisting of a filler, a labelling machine, and a capper.
 19. The test method of claim 16, wherein generating test containers comprises filling a container with a quantity of content that deviates from a nominal quantity.
 20. The test method of claim 16, wherein generating test containers comprises causing a container to have a labeling error selected from the group consisting of an incorrectly applied label and a missing label.
 21. The test method of claim 16, wherein generating test containers comprises causing a container to have a capping error selected from the group consisting of an incorrectly applied cap and a missing cap.
 22. The test method of claim 16, wherein the master unit is in network communication with the functional unit.
 23. The test method of claim 16, further comprising randomizing the specified number of test containers.
 24. The test method of claim 16, wherein the functional unit remains in operation while the inspection device inspects the test containers.
 25. The test method of claim 16, further comprising leading a randomized number of test containers past the inspection device, and wherein the inspection device generates a signal for ejecting faulty test containers.
 26. The test method of claim 16, further comprising leading a randomized number of test containers with no distinctive element or defined error past the inspection device, said test containers remaining in the container flow.
 27. The test method of claim 16, wherein generating a specified number of test containers, by the functional unit itself, comprises generating a combined test container flow, the flow having a randomized number of faulty and fault-free test containers, and wherein leading the test containers past the inspection device comprises leading the combined test container flow being past the inspection device concerned, the inspection device generating a signal for ejecting faulty test containers, whereby fault-free test containers remain in the test container flow.
 28. The test method of claim 23, further comprising automatically returning the functional unit to normal function after generating the randomized number of test containers with the distinctive element or with the defined error.
 29. The test method of claim 16, further comprising, in response to detecting an error, automatically correcting the error and minimizing possible damage resulting from the error.
 30. The test method of claim 29, further comprising, in response to detecting an error, automatically providing information on corrective action and on the automatically initiated correction of the error. 